Angles in a triangle
The angles in a triangle add up to 180°.
We can use this fact to work out missing angles in a triangle. If we know two angles, we can add these together and subtract from 180° to work out the third angle. You will often see "x" or another letter used to represent a missing angle - this is an example of algebra being used to shorten a process. It is easier to write "x" rather than "the missing angle".
An equilateral triangle is one with all sides the same length and all angles the same size (a regular shape).
We know that the angles in the whole triangle add up to 180°.
There are 3 angles in total.
One angle is 180° ÷ 3 = 60°.